Rextel dictated the tempo of the match in the first three quarters, but was threatened when Sanalva pulled within 60-65 behind the fastbreak attacks of Jeffrey Basallo, Emeriel Marquez and Galy Llamedo.
Sensing danger, Rextel's Joel Aguillon, Jeffrey Topacio and Alvin Pino countered with a flurry of bigtime shots in the closing minutes of the game to seal their victory.
Aguillon and Topacio topscored for Rextel with 16 points apiece.
Earlier, VSC lifted the third place trophy after winning be default over Big Three.
The scores
Rexteal (81) - Aguillon 16, Topacio 16, Puno 14, Mier 11, Dayondon 10, Reynes 4, Gallardo 4, Nunez 2, Villamor 2, Pancho 2
Sanalva (74) - Basallo 20, Marquez 12, Llamedo 1, Bejoc 10, Lastimosa 8, Pacaña 6, Duvera 4, Consuerga 3 - Caecent O. No-ot